Johnnie Walker is calling on a diverse cast of characters -- from actor Jude Law and a race car driver to a psychologist who studies happiness -- as it overhauls its 16-year-old "Keep Walking" campaign. The new effort will be Johnnie Walker's "largest ever global marketing campaign," according to the Scotch brand.

The new tagline, "Joy Will Take You Further. Keep Walking," moves the campaign from a work hard-and-persevere message to one that promotes the idea that joy is the key to making progress. The old tone "doesn't resonate in the way it used to," said Guy Escolme, global brand director for Johnnie Walker, which is owned by Diageo. The new campaign, he said, is meant to convey the idea "that if you start from a place of happiness, optimism and joy, it is a big accelerator of people's progress and success in their lives."

That, of course, is a pretty heady notion for a booze brand. But Keep Walking -- created by Bartle Bogle Hegarty in 1999 -- has long been into lofty ideas, such as a recent ad called "Keep Walking Lebanon" that was about "a flame that lives within all of us that can weather any storm."

The updated tone comes under Anomaly, which took over from BBH late last year as the brand's global agency of record. "The power of joy brings a transformational, new lens on progress, and one that will accelerate Johnnie Walker's momentum in culture," Karina Wilsher, CEO of Anomaly New York, said in a statement.

Mr. Escolme declined to detail spending plans on the campaign, which starts Wednesday night. But he said it would be launched on an "unprecedented" scale for the brand, touching 50 countries within its first 10 days and eventually reaching 270 million consumers globally.

A 90-second version of the first TV ad (above) includes celebrities and other personalities that the brand says exhibit a joyful outlook on life, including Mr. Law, rock group OK Go, Formula One race car driver Jenson Button, Mexican fashion model Montserrat Oliver and Eva Hakansson, a Swedish engineer and builder of the "ElectroCat" motorbike. The soundtrack is "Ca Plane Pour Moi" by Plastic Bertrand.

Also making an appearance is Johnnie Walker's master blender, Jim Beveridge. He is just the sixth master blender in the history of the brand, which was created by John Walker in 1820. "We intend to lift the lid through the course of this campaign on our blending and our blending team," Mr. Escolme said. "There's been fewer master blenders at Johnnie Walker than there have been British monarchs."

Some ads will spotlight the campaign personalities, such as this one on the artist duo Jeroen Koolhass and Dre Urhahn. They are called "Haas & Hahn" and known for creating community art that spans neighborhoods.

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And, in an unlikely twist for a liquor brand, Johnnie Walker has called on a psychologist -- Matt Killingsworth, who studies human happiness and whose work informed the new campaign, according to the brand.

The campaign includes what Mr. Escolme described as documentary-style films narrated by Mr. Killingsworth that include social experiments, such as if a positive mindset can improve someone's golf game.

The campaign comes as Diageo seeks new sales momentum on Johnnie Walker, which has been struggling. In a note to investors in July, Sanford C. Bernstein analyst Trevor Stirling called the brand's fiscal 2015 performance "weak" as organic sales declined 9%.

Mr. Escolme cited tough macroeconomic conditions, such as currency fluctuations. He also said the brand was lapping some big innovation launches, which contributed to tough year-over-year comparisons.

"We feel very confident and we feel that the future is very bright for Johnnie Walker," Mr. Escolme said. He referenced opportunities in emerging markets such as Brazil and India, where "international spirits penetration is very small" compared to developed markets. "We see significant headroom."

E.J. Schultz is the Assistant Managing Editor, Marketing at Ad Age and covers beverage, automotive and sports marketing. He is a former reporter for McClatchy newspapers, including the Fresno Bee, where he covered business and state government and politics, and the Island Packet in South Carolina. He has won awards from the Society of American Business Editors and Writers, the Jesse H. Neal Awards, the Association of Capitol Reporters and Editors, the California Newspaper Publishers Association, the South Carolina Press Association and Investigative Reporters and Editors. A native of Cincinnati, Schultz has an economics degree from Xavier University and a masters in journalism from Northwestern University.